Climate-Resilient Crops - Smallholders Facing Climate Change
Impacts and adoption of early sown wheat in Punjab and Haryana (India)
6 %
Without adaptations, global wheat yields could decline by up to 6 % for every 1°C rise in temperature 1 .
According to Ortiz-Bobea and colleagues (2021), anthropogenic climate change has led to a reduction in the world's total agricultural productivity of approximately 21% since 1961. Several studies demonstrate that anthropogenic climate change has negative impacts on global agriculture, which is directly linked to food security at both local and large-scale levels. Evidently, yield stability is crucial in the context of mounting pressure from an increasing global population and the fact that an estimated 735 million people were affected by hunger in 2022 - 122 million more than in 2019 2 .
Smallholders matter
84% of farmers worldwide cultivate less than 2 hectares of land, which corresponds to the use of 12% of the world's agricultural land 3 . According to Ricciardi et al. (2018:71), around 30-34 % of global food production can still be attributed to smallholders, which emphasizes their fundamental role in ensuring food security.
Nevertheless, only about 1.7% of the money invested worldwide in climate finance is reaching smallholders and additionally, there is a greater focus on mitigation than on adaptation 4 . The 2023 IPCC report indicates that the financial needs for global climate change mitigation are least met in the agricultural sector (Figure 2). The failure to recognize the importance of small farmers, situated within their diverse environmental and agricultural contexts, places them at a disadvantage in their ability to effectively adapt to climate change.
The early sowing of wheat represents an attempt to enhance the climate resilience of major staple crops. But how successful has this approach been disseminated and adopted - and why is it important for India?
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This story map gives context to the potentially problematic effects of a changing climate on wheat. Subsequently, wheat cultivation in India will be introduced, followed by an analysis of statistical data gathered in Punjab and Haryana (India) to answer the research question above.
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Climate change & major crops
Wheat, rice, maize, and soybean account for approximately two-thirds of human caloric intake 5 . Corresponding with this, wheat is the most widely cultivated crop, covering 219.15 million hectares in 2022 . This is followed by the arable land used to grow corn and rice, further clarifying their significance for global staple crop supply 6 . Figure 3 illustrates that cereals including the first three named crops are of particular importance in the small-scale farming sector.
Figure 3: Global crop production by farm size
The impact of climate change varies depending on the crop type.
Future maize yields could be damaged severely, while wheat cultivation may apparently experience both negative and positive consequences - this may challenge the intuitive idea that C 4 -plants (such as maize) may be more resilient to climatic changes than C 3 -plants (such as wheat), e.g. due to their higher water use efficiency.
Climate change effects are tremendously variable and it is essential to analyze climatic effects on a highly local scale.
Heat & Drought...
... as abiotic stresses are the most important adverse climate-induced factors limiting agricultural production. Their impact varies depending on the growth stage of the plant and includes morphological and physiological effects as well as plant responses at the molecular level. As illustrated in Table 1, the diverse crops demand specific temperature and irrigation requirements, which must be fulfilled to ensure a high-yield harvest.
Table 1: Requirements for optimal growth
Specific necessities, such as the optimum range of temperature, differ for each vegetative growth stage leading to diverse degrees of susceptibility throughout the plant's development. To understand the climatic problems existing for Indian wheat cultivation, we'll dive deep into the possible
...damages on wheat caused by heat & drought.
Heat stress
...can be caused by an increase in air temperature, as well as soil temperature. Additionally, plant responses are significantly dependent on extent and duration of high temperatures.
Wheat is variably sensitive to extreme heat at early stages, often leading to inhibited morphological development, such as reduced root and shoot lengths. However,
terminal heat stress
at the end of the season has been found to be the most harmful 7,8 .
Temperatures above 34°C can weaken the most vulnerable physiological event: Photosynthesis
The consequences of heat stress on wheat can include decreased leaf area expansion, damage to photosynthetic machinery, and premature leaf senescence. These alterations cause changes in the metabolic system and lead to a reduction in photosynthesis 8 .
The optimum temperatures for wheat anthesis and grain filling (late stages) have been determined to range from 12 to 22°C 7 .
Higher temperatures speed up the maturation of the spike and thus diminish the number of spikelets and grains per spike. In addition, grain shrinkage may be caused by relatively high night temperatures 8 .
Due to an acceleration of the grain-filling by heat stress, the grain-filling duration decreases which results in unstable grain weights and therefore lowered grain yields. Night temperatures of 20-23°C, for instance, reduced the grain-filling period by 3 to 7 days 8 .
To determine grain quality, grain protein content is crucial. Although grain protein content increases under heat stress - especially in early grain-filling -, the protein functionality significantly decreases, determining end-use quality 7 .
Drought
often occurs in connection with elevated temperatures. Several studies suggest that water stress is also the most detrimental during terminal heading and anthesis stages. Water limitation contributes to a reduction in the number of grains and grain weight as well as failures in pollination, disrupting the plant's reproduction.
Moreover, in this late phase, evapotranspiration is maximum, which exacerbates the situation and induces severe crop loss 9 .
Wheat in general has a comparatively low water requirement, but severe water stress decreases grain yields - however, it is important to note that there is inconsistency in the use of such classifications due to ambiguous factors, such as the soil type and the experimental environment 9,10 .
Vulnerability to heat can be considered high - especially during terminal stages.
Wheat cultivation in India
With 106.84 million tonnes (2022), India is the second-largest wheat producer worldwide, trailing only China 11 . What is unique about India's wheat is that the vast majority, exceeding 98% (2021), is consumed domestically by its population of 1.4 billion people. Imports typically remaining close to zero 12 .
On the right map, one can clearly see the very fertile so-called Indo-Gangetic Plain in the South of the Himalayas (red colors, legend at the bottom left) comprising Northern India, but also parts of Bangladesh, Nepal, and Pakistan. It is one of the most fertile regions in the world and of major importance for India's agriculture.
The country's self-sufficiency with its major staple foods, rice and wheat, is often referred to as "one of the greatest success stories of Green Revolution" 13 , ensuring the nation's food security. By adopting modern technologies in irrigation, pesticide use, or fertilization, coupled with the development of new wheat varieties, India was able to increase its wheat production from around 6.5 million tonnes in 1950 to today's level - equating a rise of 1544% 13 (Figure 5). The All India Coordinated Wheat Improvement Project (AICWIP), today named All India Coordinated Research Project (AICRP) on Wheat and Barley, started in 1965 was of major significance for a rise in productivity by releasing high-yielding varieties like HD 2967 or HD 3086 15 (Figure 6).
Figure 6: Increase in productivity after establishment of AICRP
According to Tripathi and Mishra (2017:275), 85% of India's farms own approximately 1.3 hectares of arable land, which makes smallholder farmers the main actors for success 27 .
Wheat production (tonnes) and area (hectares, map) is led by the states of Uttar Pradesh, Madhya Pradesh, and Punjab, ...
... while the highest yield-productivity (kg/hectare) is achieved in Punjab and Haryana (green frame).
As can be seen in Figure 7, Punjab and Haryana are the only states where production shares exceed area shares. This underscores the exceptional fertility and productivity of the region.
The heart of Indian agriculture: Rice-wheat crop rotation
The rice-wheat cropping system represents the most prevalent agricultural cultivation practice in South Asia. In India, three species of wheat are cultivated: Winter wheat (Triticum aestivum; also 'Bread wheat') represents 95% of the total wheat grown, while Triticum durum and Triticum dicoccum are only of marginal importance (4% & 1%) 13 . Given the crucial role of the local climate in agriculture, the Indian agricultural calendar is structured around the monsoon season, which is characterized by heavy rainfall. Especially in rain-fed cultivation areas, summer monsoon is of key significance.
Kharif: JUN - JUL - AUG - SEP - OCT
Kharif season is defined by the rain-bearing Indian summer monsoon. The cultivated crops typically require a large amount of water. Rice (Oryza sativa) is the most important Kharif plant, as it is India's second staple food for self-sufficiency but e.g. maize or cotton also play a secondary role 11,13 .
Rabi: NOV - DEC - JAN - FEB - MAR - APR
During post-monsoon Rabi season, the major cultivated crop in India is wheat, along with barley, lentils, or potatoes. The Rabi period also depends indirectly on the monsoon because it determines when fields are ready for sowing again. To ensure a successful Rabi harvest, irrigation became a common method and today, about 95% of India's wheat areas are under irrigation 11,12 .
Zaid/Jayad: MAR - APR - MAI - JUN
The term Zaid is used to refer to the summer season, defined as the brief period between the Rabi and Kharif crop seasons. The sowing of Zaid crops occurs in March or April, depending on the harvest of the Rabi crops. The gap-filler crops require dry and warm weather as well as longer day lengths. Exemplary crops include cucumber, watermelon, pumpkin, or pulses 14 .
How climate endangeres food security
With all the knowledge gained above, it can be inferred that Indian small-scale farmers are more dependent of climatic phenomena than many others.
So what if... climate changes?
Monsoon variability
As explained above, Indian agriculture is highly reliant on the monsoon season. Numerous studies have already focused on alterations in the occurrence of the monsoon:
- Auffhammer and colleagues (2012) posit that over the past half-century, the total rainfall in the months of June to September has weakened, with the rate of decline accelerating over time. Furthermore, it has been observed that the distribution of precipitation within the monsoon season has become increasingly extreme. The study demonstrates that climate variability affect agricultural outcomes significantly: cumulative Kharif rice yield would have been 5.67% (75 mio. tonnes) higher between 1966 and 2002 without climate change 16 .
- A decreased monsoon not only affects Kharif crop harvests, it maintains soil moisture budget for the whole year. Particularly, peak monsoon rainfall determines healthy crop production 17 .
- Through less rainfall and more extreme climate events like droughts, irrigation becomes increasingly important, putting serious pressure on ground water ressources 18 .
Figure 8: Trend in rainfall during rice-(left) and wheat-growing (right) periods in Punjab, 1986–2015
Terminal heat stress
"Wheat growing in India is a gamble in temperature."
The early observation, which remains valid until today, clarifies that wheat cultivation is constrained by temperature at the beginning and end of the cropping season. The region's proximity to the equator and the popular rice-wheat crop rotation, which includes delayed wheat sowing, cause high temperatures (surpassing 35°C) at the end of the reproductive stage, with consequences described in section 2 . Additionally, the northwestern plains are even more prone to intense temperature stress due to dry winds from the Thar Desert 13 .
Figure 9: Trend in mean temperature during rice- and wheat- growing periods in Punjab, 1986–2015
As visible in Figure 10, yield potential of wheat declines the later it is sown because of the shortened maturation 19 .
Figure 10: Sowing date and wheat yield potential. A break point is shown on DOY 324 (~ Nov. 20th)
Climate Change(d) - already today: Heat wave 2022
In the months of March and April 2022, an extreme heat wave brought temperatures 4.5 to 8°C above normal along with significantly decreased rainfall. The extreme event coincided with grain-filling, resulting in yield losses of up to 15% 20 .
It was the hottest March on record since the Indian Meteorological Department (IMD) began maintaining records 122 years ago 21 .
Early sown wheat in Punjab & Haryana - a possible solution
In the past, the release of high-yield varieties has impacted India's agricultural production profoundly. Against the background of a changing world's climate, focusing on the development of increasingly heat-tolerant wheat varieties is crucial.
A way to avoid damage due to terminal heat and water stress is the forward shifting of the entire cultivation cycle, including harvest. Instead of sowing in late November and December - the conventional way - an early sowing in October and early November shall be achieved. For this purpose, suitable varieties require a higher heat tolerance in the early stages. Recently, such early sown wheat (ESW) varieties were released and disseminated in different regions. The 2020 launched DBW 187, DBW 303 and WH 1270 appear to be the first varieties specifically developed for October sowing in India 22 .
To gain an idea of the actual spreading and adoption of ESW, Dominik Naeher and his colleagues gathered data about the utilization of early sown wheat varieties by surveying 1206 households located in Punjab and Haryana.
Figure 11: Left: Communities exhibiting signs of early wheat sowing (green). Right: Districts, these communities are concentrated in and selected for the study
Using remote-sensing data, the researchers identified areas containing pixels of sown wheat already in October - mid-November. Based on this information, seven districts were selected as a sampling frame: Amritsar, Hoshiarpur (Punjab), Gurugram, Kurukshetra, Mahendragarh, Nuh and Rewari (Haryana) contained more than 70% of the early sowing communities 22 .
Results of data analysis
The following results refer to the data provided by Naeher et al. (2023) which can be accessed by clicking on the following: ACCESS DATA . Learn more about the methods used and jump to Section 6 .
In order to gain insight into the study's farming population, Figure 12 shows the distribution of field areas for the largest cultivated plot in hectares. 93.9% operated within the range of 0 - 5 hectares in the Rabi season 2021/22.
Despite indications that early sown wheat is being used in the communities under study, only 6% (n=72) have heard of ESW varieties. Within this 6%, the most common sources of perception were other farmers in the village (44.4%), or friends and family (16.7%). Governmental advisory agents only accounted for 12.5%.
Regarding the question of who they would ask for advice or information on how to best use ESW, 'other farmers in the village' and 'friends and family' were also the most frequent answers.
Of the 72 smallholders who have heard of ESW, 85% think that October is the ideal starting date for sowing ESW (given July-December as options). In light of this, one would infer that a relatively good familiarity with the utilization of ESW is present.
Moreover, the farmers were asked how they perceive the impacts of ESW compared to conventional sowing. Since this question was also of conditional appearance to farmers who have heard of ESW, the answers are related to the 6%.
In terms of cultivational techniques, such as timing or labor time, the majority of the interviewed farmers did not perceive a significant difference. However, it is notable that the majority of farmers felt that grain yield was higher with ESW varieties, and that more than 30% saw a higher profit for farmers. Additionally, 20.6% of farmers believed that the amount of water needed for irrigation was smaller. These findings suggest that the smallholders who were aware of ESW see advantages, or at least no drawbacks, in using it.
The actual number of farmers who are not only aware of ESW varieties but who have already utilized them is 51, representing 4.5% of the entire sample. However, even if they have not planted ESW before but have heard of it, there is a moderate statistically significant correlation indicating that they harvest earlier than those farmers who have never heard of it.
Figure 15: Reasons for non-adoption or discontinuation of ESW. Own figure.
If the smallholders have never used it but heard of it or stopped using it after the first time, they were asked about their reasons, which can be in Figure 17 (Multiple answers possible, n=30). Contradictory to the assumption above, a lack of information about ESW varieties was the main reason selected (Figure 15).
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Insertion: Why does not just every farmer sow as early as October or early November?
McDonald and colleagues (2022) conducted a household study throughout 2010-2015 which comprised 5,766 responses. The researchers discovered that the main causes for delayed sowing (> November 15th) were that the field was still occupied by the previous crop (44%), primarily rice, followed by a lack of knowledge about the importance of early sowing (26%) and field waterlogging from poor drainage (21%). Disaggregating the data by survey periods (2010-2012 & 2013-2015) showed that the knowledge gap of late-sowing farmers decreased significantly while the occupation by rice more than doubled. The authors attributed this to a delay in the monsoon onset 19 .
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It is not involved in Naeher et al.'s study if there were similar issues like waterlogged fields. However, it was tried to consider the wheat-rice tandem. When asked for the crop grown in the preceding Kharif season, 34% of farmers planted millets, while 46.1% cultivated rice (Basmati and coarse). 87% of the rice was harvested in October (27.7% in week 1, 34.4% in week 2, 28.3% in week 3 and 9.6% in week 4). The arithmetic mean of the fallow time before growing wheat is 2.2 weeks. This suggests that an occupied plot causing delayed sowing is possible, but small in Punjab and Haryana - depending on monsoon variability.
Wheat varieties used in the sampling area
With 46.2% of the primarily wheat-cultivating smallholders using HD 2967, it was the most popular wheat variety used in the 2021/22 season. The following places are occupied by WH 711 (8.3%), SRM 272 (6.7%) and DBW 187 (5.8%). The 'Other:'-space was found to contain more than 80 different other varieties, underscoring the considerable heterogeneity of wheat varieties on the market.
Figure 16: Selected types of wheat varieties sowed during Rabi season 2021/22. Own figure.
One interesting aspect of the used wheat varieties is that it is not unambiguously clear which varieties are used as early sown ones only. In total, only 3.3% state that early sown wheat was used (Figure 17). Taking a closer look at those few farmers (n=34), they mainly cultivated the varieties DBW 187 (32.4%) and HD 2967 (20.6%). After that follows an 'Other:'-Specification, stated as "306", perhaps meaning C 306 (16.7%).
The vast majority of those using HD 2967 and DBW 187 classified them as Old OPV instead of early sown variety.
Lamba and colleagues (2023) provide more detailed information on the most widely grown wheat variety in relation to heat stress. The researchers found that HD 2967 was high yielding under both conditions, normal conditions when sown normally (November 14th) and heat stress conditions when sown late (December 15th). Overall, it was the most productive of the 50 varieties tested under heat stress 23 .
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Conclusion
As explained above, climate change could have tremendous consequences on Indian wheat and rice-focused agriculture without adaptation strategies. To date, agricultural productivity has kept pace with population growth, but several authors warn that food security may be at risk.
-The mostly cultivated variety was HD 2967, representing an improved heat-tolerant genotype in regard to terminal heat stress.
-The most prevalent ESW variety (if practiced early sowing) was DBW 187.
-A Considerable majority has never heard of ESW varieties, highlighting the lack of intensified information spreading
-Since the main source of information appears to be other farmers, addressing them directly, to also decrease their own insecurities concerning ESW, seems to be of key significance
-The fact that those farmers who are aware of ESW perceive the impacts as positive demonstrates that there is potential for further enhancement of the country's agricultural climate resilience - but it needs to be fostered on a broad, holistic scale.
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Methods
The correlation between the variables “scc1: Have you heard of early sown wheat varieties, which can be sown earlier (in October) compared to the conventional sowing (in November) in order to avoid harvest failures caused by terminal heat and water shortages which often occur at the end of the wheat harvest season?” & “sff5m: When did you harvest the wheat on this plot in Rabi season 2021/22 (month)?” was analyzed with the Cramer’s V correlation measure. The level of significance was determined to be 0.01 and between 0.20 and 0.40, Cramer’s V can be interpreted as moderately related 24 .
Figure 18: Result Cramer's V analysis
